Such a tool is employed in actual practice for tightening or loosening the wing nuts of a central wheel lock, particularly of classical automobiles. For this purpose, special wooden tools for wing nuts are known that allow an approximately positive fit of the wing nut that secures the wheel of a motor vehicle. Here, the wooden wrench is configured as a wooden board having a slot that matches the contour of the wing nuts.
A drawback of such a wooden tool is the lack of protection against axial slippage. Here, it has also proven to be problematic that, in the case of a central wheel lock for motor vehicles, especially for wheels with spokes, the wings do not lie in a plane parallel to the axis of rotation, but rather, they essentially exhibit a slight pitch with respect to the plane that is crosswise with respect to the axis of rotation. This results in essentially undefined contact surfaces whose inclination further promotes the tendency towards slippage. Moreover, such wooden wrenches can only transfer low torques, in addition to which their magnitude cannot be reliably reproduced.
Therefore, such wing nuts for central wheel locks are loosened and tightened with a copper hammer even nowadays, so that it is essentially a matter of the skill of the mechanic to ensure that sufficient torque is applied. Moreover, in the long run, the stress caused on the wing nuts by such blows with a hammer results in visible and thus undesired damage to the surface.
Likewise known are various hand-held tools designed for tightening and loosening different types of wing nuts and the like for various application purposes.
For example, U.S. Pat. No. 5,697,268 relates to such a tool whose base element is followed by a shank that is configured as a hollow body and that has slit-like slots of different widths that are arranged in pairs across from each other so that all kinds of wing nuts can be reliably tightened or loosened. Here, the slots also form the contact bodies for each wing. A section of the base element located across from the shank serves to receive a commercially available wrench.
A tool known from German utility model G 93 18 159 U1 likewise has a shank that has connection means for transferring the torque, for instance, a bore for a lever or a plug-in connector for a universal tool, and whose other end is configured as an open pipe having two slit-shaped slots located across from each other and open towards the end of the tool that are designed to receive the wings of the wing nut or wing screw.
A tool configured as a socket wrench for tightening and loosening a wing nut is also described in German utility model G 87 01 555 U1, two elongated slots being located in a cylindrical socket wrench made of metal or a metal-like material, and the dimensions of said slots corresponding to the thickness of one wing of the wing nut. The cylindrical socket wrench is coated with plastic.
German utility model G 88 14 967 likewise discloses a wrench for wing nuts or castellated nuts of screw jacks used in concrete construction. For this purpose, the wrench has a sleeve with at least one pair of cams on its jacket, said cams projecting over the free front surface of the sleeve and interacting with the edges of the wings of the wing nut.
Furthermore, German utility model DE 200 02 763 U1 describes a socket wrench for mounting and dismounting a wing nut used for toilet seat brackets. For this purpose, the socket wrench is configured essentially hollow and has two grooves offset by 180° which serve to receive the wings of the wing nut. In order to transmit force, a sunk rectangular hollow body that serves to receive a ratchet can be used in addition to a metal pin.
Moreover, German utility model DE 295 19 672 U1 relates to a wrench for screwing and unscrewing wing nuts or hex nuts of the type employed for locking utility and electricity meters of power supply companies in a secure manner with a lead seal.